1. Field of the Invention
The present invention relates to a semiconductor integrated circuit device. In particular, it relates to a structure of a semiconductor integrated circuit device, wherein a signal can be transmitted in a non-contact manner without using a bump.
2. Description of the Related Art
Conventional examples of common methods for mounting a semiconductor integrated circuit device include flip chip mounting and wire bonding. In these methods, electrically conductive joint members, e.g., bumps and wires, for connecting semiconductor integrated circuit devices to circuit boards are physically joined to electrodes of semiconductor substrates and, thereby, electrical signals are transmitted in a conduction state.
For example, as shown in FIG. 5, which is a sectional view of a key portion of a semiconductor integrated circuit device, an opening 104 is formed in a passivation film 105 covering a substrate main body 129 of a semiconductor substrate, a substrate layer 130 is formed on the uppermost layer wiring 103 exposed at the opening 104 and in the periphery of the opening 104 from an electrically conductive material, and a solder bump 102 is joined to the substrate layer 130. The passivation film 105 prevents moisture absorption of insulating layers (not shown in the drawing) laminated on a principal surface of the semiconductor substrate and an occurrence of short-circuiting between the uppermost layer wirings 103 (refer to Japanese Unexamined Patent Application Publication No. 11-243109).
However, in the case where the semiconductor integrated circuit device is miniaturized, adjacent joint members (bumps or the like) come into contact with each other, so that short-circuiting may occur. Therefore, there is a limit to the amount of miniaturization of the semiconductor integrated circuit device.
On the other hand, a method in which a signal is transmitted in a non-conduction state through the use of capacitive coupling has been proposed. For example, as is indicated in a sectional view shown in FIG. 6, in a modular electronic system 201, for example, a dielectric 217 is filled in a gap between “half capacitors” 214 and 215 and serves as a means 213 for signaling capacitively so as to provide a capacitive signal path between substrates 210 and 211 (refer to, for example, Japanese Unexamined Patent Application Publication No. 2004-253816).
In the case where capacitive coupling is used, joining with an electrically conductive member becomes unnecessary and, therefore, it is easy to prevent an occurrence of short-circuiting.
However, if the area of the pad on the semiconductor substrate side is reduced along with miniaturization of the semiconductor integrated circuit device, a capacitive region between the pad and an electrode formed on the circuit board becomes small and, therefore, there is a problem in that a desired capacitance is not obtained.